head unit

[Anthony Pray] had his car stereo stolen. When thinking about replacing it he realized the he and his wife never used it for anything other than an Auxiliary connection to play songs from their cellphones. So instead of buying a head unit he pulled an unused home audio amplifier out of a dark corner of his house and wired it to the car speakers. Problem solved, except that the under-dash installation meant the only volume control is on the phone playing the audio. He decided to build a wireless audio controller that would let him send commands to the phone without quite as much distraction from the road.

The device you see above is his creation. What a beauty. But seriously, it’s so random and hacked together how can you not love it? And, it works!

The frame is made from plastic coat hangers, and the wheel is an old RC control knob. There’s even a play/pause feature built from the clicking properties of a retractable ball-point pen. A Cypress PSoC board reads the knob and pen positions, then pushes commands via a Bluetooth module in order to control the phone. He recorded a testing video (after the break) which gives you a better look at the functionality of this setup. Continue reading “The Rube-Goldberg of car audio”→

The stereo head unit design was changed between the 2004 and 2005 model years, so while he had a good idea of what to look for, he had to find the proper components on his own. Once he identified the radio module, he was able to locate the left an right input pins through trial and error. He carefully soldered a 3.5” audio jack to the head unit’s input lines, wiring it to cut off the audio signal from the radio whenever his Zune was plugged in.

Everything was reassembled, and the input jack was inconspicuously mounted in a cubby hole just above the stereo. [mukmuk] is quite happy with his modification, and we’re guessing his road trip was far more pleasurable as a result of his work.

[Dave] pulled the head unit out of his dashboard to add an iPod input. He took a much more invasive route than the other hack we saw a few days ago. He actually patched into the audio lines going from the Dolby reader head chip to the amplifier.

The first step was to trick the deck into thinking it had a cassette inserted. He scoped an enable pin on one of the chips to discover the timing and emulated that signal using a PIC microprocessor. From there he popped off the chip that reads the tape data, patching directly into the audio out traces. This presented some noise issues when charging the iPod but [Dave] fixed that with some decoupling capacitors.